Born in Tokyo in 1916. In 1930, she joined the Tokyo Shochiku Drama Department, and in 1934 entered Shochiku Kamata along with Aizome Yumeko, who was supposed to have debuted in Fuji Films' America Koro. Mizukubo's debut at Shochiku Kamata was alongside Wakamizu Kinuko and Aizome Yumeko as one of three sisters with differing personalities in the film Mushibamameru Haru, directed by Naruse Mikio. She later appeared in two more films directed by Naruse Mikio-Kimi to Wakarete and Boku no Marumage - and showed her compatibility with the director. These films also turned out to be some of her best work. Her small size and the shape of her lips invited comparisons to a popular foreign actress of the day and earned her the nickname of "the Japanese Sylvia Sidney." Later, Mizukubo starred in Arashi no Naka no Shojo, under director Shimazu Yasujiro. She subsequently appeared in Shimazu Yasujiro's Hijosen no Onna, Chocolate Girl, starring Yuki Ichiro, and others. Mizukubo also tried her hand at comedy, appearing with Fujii Ko in such films as Genkanban to Ojosan, and also played a young geisha apprentice in Tsukigata Hanpeita, starring Hayashi Chojiro. After a stint at Shochiku Shimogamo, Mizukubo joined Nikkatsu Tamagawa, where she played Suzuki Denmei's love interest in Wakafufu Shiken Shibai and appeared in Ganto no Shojo and Gurentai no Uta, among others. With Kyodo Films, she worked with Aizome Yumeko in such films as Nichizo Getsuzo and Mittsu no Shinju. In 1935, during shooting of Midori no Chiheisen, Mizukubo attempted suicide in response to trouble in her marriage. She then disappeared from the film world.